The present invention relates to the field of photography and, more specifically, to photographic apparatus, such as a self-developing camera back for a 4.times.4 view camera, including a film processing assembly for effecting distribution of a fluid processing composition between superposed sheets of a self-developing film unit.
Self-developing camera backs for use with large format view cameras are, of course, well known in the prior art.
For example, Polaroid Corporation, Cambridge, Mass., presently markets a camera back designated Polaroid Land Pack Film Holder Model 405 that holds a pack of eight 107 or 108 Polaroid Land Film units. These film units have an image area of approximately 3.25".times.4.25". Generally, these camera backs are used with view cameras having a similar or slightly smaller image area format.
Until recently, larger 4".times.5" format self-developing film units had not been available in multiple film unit packs. Instead, these film units were packaged as single units. Therefore, self-developing 4.times.5 camera backs for use with 4.times.5 cameras heretofore have been configured to receive these single film units rather than a film pack. Examples of such 4.times.5 self-developing camera backs may be found in commonly-assigned U.S. Pat. Nos. 2,933,993 and 3,505,939.
Alternatively, the smaller format 405 camera back may be modified for use with a 4.times.5 view camera by providing an oversized adapter plate on the front thereof. However, the use of the smaller format film precludes recording the full image provided by the camera's optical system. An example of a modified 405 pack holder for use with a 4.times.5 view camera may be found in commonly assigned U.S. Pat. No. 3,852,780.
The camera back disclosed in this last-mentioned patent includes an elongated housing having a film withdrawal opening and pull tab slot at one end thereof. In response to pulling on a tab extending through the pull tab slot, the leader of the exposed film unit is advanced through the film withdrawal slot. In response to pulling on the leader, the exposed film unit is advanced between a pair of pressure applying rollers which release a fluid processing composition from a pod at the leading end of the film unit and distribute the fluid between superposed negative and positive sheets of the film unit. An exposure aperture in the forward wall of the camera back may be selectively blocked and unblocked by a dark slide which is pulled out from the opposite end of the housing. Because this smaller format camera back is not as long as the film holder section of a 4.times.5 camera, the end having the dark slide slot therein is spaced from a camera back or film holder locating stop so that the dark slide may be easily removed. However, if a camera back is suitably dimensioned to fit into the film holder section of a 4.times.5 camera, this positioning stop would preclude, or at least make difficult, locating the dark slide at this end of the camera back.
Because 4.times.5 self-developing film units are now being packaged in a multiple film unit pack, there is a need for a full size pack holding camera back that is suitable for use with most commercially available 4.times.5 view cameras.
The camera back disclosed in the previously-noted U.S. Pat. No. 3,852,780 employs a film processing assembly including a support frame having mounted thereon a pair of pressure-applying rollers, edge control structure for applying a compressive pressure selectably to the lateral edges of the film unit to prevent fluid leakage therefrom as the film unit is advanced through the pressure applying rollers, and a ramp-like inclined film guide for guiding the film unit toward the edge control structure and pressure-applying rollers. The film processing assembly is adapted to be snap fit into the camera back housing so as to be readily removable therefrom to facilitate cleaning the rollers.
This type of removable film processing assembly is described and shown in more detail in commonly assigned U.S. Pat. No. 3,745,904. While this film processing assembly performs well, it is generally more mechanically complex and more costly to assemble than is desirable.
Therefore, it is an object of the present invention to provide a pack holding self-developing camera back that is suitable for use in a wide variety of 4.times.5 view cameras.
It is another object to provide such a camera back having a dark slide arranged thereon so as not to interfere with camera back or film holder locating structure on such view cameras.
Yet another object of the invention is to provide such a camera back having a film processing assembly that is readily removable for cleaning purposes.
Another object is to provide a film processing assembly for use in such a camera back that is simple in its construction and may be easily assembled.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.